Multiple sclerosis (MS) and its different forms are Studied in the animal model experimental autoimmune encephalomyelitis (EAE). Relapsing-remitting MS. the most common form of the disease can be induced in mice where clinical symptoms fluctuate in severity over time. However. the animal model does not experience periods of recovery where clinical signs are absent, unlike the human disease. We have developed a novel model of relapsing-remitting EAE in C57BL/6 mice immunised with myelin oligodendrocyte glycoprotein (MOG) peptide and Quil A as adjuvant. These animals have relapses that are followed by periods of recovery, during which time the animals do not exhibit illness. Furthermore. administration of the PPAR gamma agonist pioglitazone prior to a predicted relapse prevents the expected development of symptoms in a dose-dependent fashion. Immune cell infiltration into white matter of the CNS and decreased production of inflammatory cytokine IFN-gamma in treated animals were also observed. Our model will be a valuable tool in assessing intervention therapies for RR-MS sufferers. (c) 2007 Elsevier B.V. All rights reserved.